Devices and methods for preventing distal embolization using flow reversal and perfusion augmentation within the cerebral vasculature

ABSTRACT

A medical device having a catheter and one or more expandable constricting/occluding members. The catheter is adapted for use with therapeutic or diagnostic devices, including an angioplasty/stent catheter and an atherectomy catheter. A first constrictor/occluder mounted at the distal end of the catheter is adapted for placement in a brachiocephalic or subclavian artery. A second constrictor mounted proximal to the first constrictor/occluder is adapted for placement in the descending aorta. Pressure measuring devices may be included, and filters may be used to capture embolic debris. Methods of using the devices for preventing distal embolization during extracranial or intracranial carotid procedures or vertebral artery procedures by augmenting collateral cerebral circulation by coarctation of the aorta to enhance reversal of blood flow in an internal carotid artery, an external carotid artery, and/or a common carotid artery toward the subclavian artery are disclosed.

FIELD OF THE INVENTION

The present invention relates generally to devices and methods useful intreating patients with stroke or occlusive cerebrovascular disease. Morespecifically, the invention provides an extracranial device capable ofreversing flow down a vertebral artery, an internal carotid artery, anexternal carotid artery and/or a common carotid artery, and into thesubclavian artery during an invasive procedure, thereby avoiding distalembolization of vascular debris. Various diagnostic or therapeuticinstruments, including an angioplasty catheter, stent deploymentcatheter, atherectomy catheter, and/or a filter, can be introducedthrough the device for treating the occlusion. The invention may also beuseful to reverse flow and pull back embolic debris during a stroke.

BACKGROUND OF THE INVENTION

Stroke is the third most common cause of death in the United States andthe most disabling neurologic disorder. Approximately 700,000 patientssuffer from stroke annually. Stroke is a syndrome characterized by theacute onset of a neurological deficit that persists for at least 24hours, reflecting focal involvement of the central nervous system, andis the result of a disturbance of the cerebral circulation. When apatient presents neurological symptoms and signs that resolve completelywithin 1 hour, the term transient ischemic attack (TIA) is used.Etiologically, TIA and stroke share the same pathophysiologic mechanismsand thus represent a continuum based on persistence of symptoms andextent of ischemic insult.

Outcome following stroke is influenced by a number of factors, the mostimportant being the nature and severity of the resulting neurologicdeficit. Overall, less than 80% of patients with stroke survive for atleast 1 month, and approximately 35% have been cited for the 10-yearsurvival rates. Of patients who survive the acute period, up to 75%regain independent function, while approximately 15% requireinstitutional care.

Hemorrhagic stroke accounts for 20% of the annual stroke population.Hemorrhagic stroke often occurs due to rupture of an aneurysm orarteriovenous malformation bleeding into the brain tissue, resulting incerebral infarction. The remaining 80% of the stroke population arehemispheric ischemic strokes and are caused by occluded vessels thatdeprive the brain of oxygen-carrying blood. Ischemic strokes are oftencaused by emboli or pieces of thrombotic tissue that have dislodged fromother body sites or from the cerebral vessels themselves to occlude thenarrow cerebral arteries more distally. The extracranial or intracranialinternal carotid artery, commonly affected by atherosclerosis causingsymptomatic occlusion in the arterial lumen, is often responsible forhemispheric ischemic stroke and generating thromboembolic materialdownstream to the distal cerebral vessels. Proposed treatment of theoccluded carotid artery in patients with stroke and TIA, or for strokeprevention in patients with asymptomatic flow limiting carotid stenosis,includes angioplasty, stent placement, or atherectomy on the occludedcarotid artery. This is also true of the vertebral artery.Unfortunately, placing instrumentation within a diseased artery isassociated with increased risk of ischemic stroke, since manipulation ofan atheromatous plaque in the arterial wall often causes emboli todislodge distally in the narrow cerebral arteries.

Current methods of preventing distal embolization from carotidinstrumentation include insertion of a blood filter distal to theocclusion and suctioning embolic debris during the procedures.Disadvantages associated with the conventional methods are that (1)inserting a filter through the atheromatous lesion is associated withincreased risk of distal embolization, (2) using suction to reverse theflow in the internal carotid artery may increase a patient's blood lossif the suctioned blood is discarded, and (3) systemic anticoagulationand pumping may be required to recycle the suctioned blood back into thearterial or venous system, and such anticoagulation is associated withincreased risk of hemorrhage.

New devices and methods are thus needed for patients undergoing carotidprocedures for definitive or prophylactic treatment of carotid plaque,which minimize the risk of distal embolization and prevent ischemicstroke.

SUMMARY OF THE INVENTION

The invention provides devices and methods for preventing ischemicstroke in patients undergoing percutaneous invasive vertebral or carotidprocedures, including angioplasty, stent placement, atherectomy, and/orfilter insertion, by reversing blood flow down a vertebral artery, anextracranial or intracranial internal carotid artery, an externalcarotid artery, and/or a common carotid artery and into the ipsilateralsubclavian artery. In this way, embolic debris generated as a result ofplacing instrumentation within a diseased artery is diverted to thesubclavian artery, thereby preventing stroke by minimizing distalembolization to the narrow cerebral vessels. The devices and methods arealso useful to remove an embolus and improve flow (by reversingcollateral blood flow across the circle of Willis) in patients withacute stroke.

The invention utilizes devices comprising a catheter having anexpandable constricting member at its distal end. The constrictor may bea balloon, in certain cases a toroidal balloon, or a device of any otherappropriate shape, so that it can fully or partially occlude blood flowin a blood vessel, e.g., the common carotid artery, the subclavianartery, the brachiocephalic artery, and the aorta. The lumen of thecatheter may be adapted for insertion of a therapeutic instrument, suchas an angioplasty, atherectomy, and/or stent catheter. A manometer isoptionally mounted proximal and/or distal to the constricting member formonitoring blood pressure proximal and/or distal the constrictor. Theproximal end of the catheter may include a hemostatic valve.

In another embodiment, the catheter includes a firstconstrictor/occluder and a second constrictor, each on respective firstand second elongate members. The first and second constrictors arecollapsed to facilitate insertion into and removal from the vessel, andexpanded during use to restrict blood flow. When expanded, theconstrictors may have a maximum periphery that conforms to the innerwall of the vessel, thereby providing a sealed contact between theconstrictor and the vessel wall. The devices can optionally include amanometer and/or pressure limiter to provide feedback to the variableflow mechanism for precise control of the upstream and downstream bloodpressure. In certain embodiments, the constrictor includes a secondlumen for passage of other medical devices. Devices such as an infusion,atherectomy, angioplasty, stent placement, or electrophysiologic study(EPS) catheter, can be introduced through the constrictor to insert inthe vessel to provide therapeutic intervention at any site rostrally.

In still another embodiment, the catheter includes a second lumencommunicating with a proximal end and an infusion port at its distalend. The port is located distal to the distal port of the catheter. Thesecond lumen and its port are adapted for delivering a pharmaceuticalagent to the carotid, brachiocephalic and/or subclavian arteries,including an angiographic dye. Any device described in Barbut, U.S. Pat.No. 6,146,370, and Barbut, U.S. application Ser. No. 09/260,371, filedMar. 1, 1999, both incorporated herein by reference in their entirety,may also be used in the methods described herein.

The invention provides methods for reversing flow in a vertebral orcarotid artery having an atheromatous lesion. More specifically, themethods are useful in reversing flow down a vertebral artery, anextracranial or intracranial internal carotid artery, an externalcarotid artery, and/or a common carotid artery and into the subclavianartery, and optionally into a filter located in the subclavian artery.In a first method of using the devices described above, the distal endof the catheter is inserted into the right brachiocephalic artery. Thefirst catheter can be inserted over a guidewire through an incision on aperipheral artery, including the femoral artery, the subclavian artery,or the brachiocephalic artery. The catheter is positioned to locate theconstricting member within the right brachiocephalic artery. Preferably,the constrictor is expanded to completely or partially occlude the rightbrachiocephalic artery. A second constrictor carried by a secondcatheter is located in the aorta downstream of the left subclavianartery. The second constricting member is expanded to partially or fullyocclude the aorta, thereby augmenting blood flow to the left commoncarotid artery, the left subclavian artery, and the left vertebralartery.

It will be understood that coarctation in the aorta increases thepressure gradient from the left cerebral arteries to the right cerebralarteries, thereby enhancing flow reversal in the right cerebral arteries(including the right CCA, the right ICA, the right ECA, and the rightvertebral artery). At a critically low brachiocephalic pressuredownstream or distal to the constriction, blood flow in the carotid andvertebral arteries is reversed to pass over the atheromatous lesion andinto the right subclavian artery. The flow reversal can be verifiedfluoroscopically with dye.

It will be understood that either or both of the aortic constrictor andthe brachiocephalic constrictor may be inserted through an incision inthe femoral artery. In certain cases, the brachiocephalic constrictingcatheter is inserted through the catheter that carries the aorticconstrictor. Alternatively, the aortic constrictor may be insertedthrough the femoral artery and the brachiocephalic constrictor may beinserted through the right or left subclavian artery. In a furtheralternative, both the brachiocephalic constrictor and the aorticconstrictor are inserted through the right or left subclavian arteries.

In another method, a coarctation constrictor is positioned in the aortaupstream or downstream of the left subclavian artery, and a secondconstrictor is positioned in the right subclavian artery upstream of theright vertebral artery. The second constrictor is expanded to reducepressure distally in the right subclavian artery. The coarctationconstrictor is expanded to augment cerebral blood flow to the leftsubclavian artery, the left CCA, the right brachiocephalic artery, andthe right CCA. It will be understood that coarctation in the aortaincreases the pressure gradient from the left cerebral arteries to theright vertebral artery, thereby enhancing flow reversal in the rightvertebral artery. At a critically low right subclavian pressuredownstream or distal to the constriction, blood flow in the vertebralartery is reversed to pass over the atheromatous lesion and into theright subclavian artery. The flow reversal can be verifiedfluoroscopically with dye. It will be understood that either or both ofthe aortic constrictor and the subclavian constrictor may be insertedthrough an incision in the femoral artery. Alternatively, the aorticconstrictor may be inserted through the femoral artery and thesubclavian constrictor may be inserted through the right subclavianartery. In a further alternative, both the subclavian constrictor andthe aortic constrictor are inserted through the right or left subclavianarteries.

In another method, a coarctation constrictor is positioned in the aortaupstream or downstream of the left subclavian artery, and a secondconstrictor is positioned in the left subclavian artery upstream of theleft vertebral artery. The second constrictor is expanded to reducepressure downstream or distally in the left subclavian artery. Thecoarctation constrictor is expanded to augment cerebral blood flow tothe right subclavian artery, the left CCA, the right brachiocephalicartery, and the right CCA. Coarctation in the aorta increases thepressure gradient from the right cerebral arteries to the left vertebralartery, thereby enhancing flow reversal in the left vertebral artery. Ata critically low left subclavian pressure downstream or distal to theconstriction, blood flow in the left vertebral artery is reversed topass over the atheromatous lesion and into the left subclavian artery.The flow reversal can be verified fluoroscopically with dye.

In another method, a coarctation constrictor is positioned in the aortaupstream or downstream of the left subclavian artery, and a secondconstrictor is positioned in the left common carotid artery. The secondconstrictor is expanded to reduce pressure downstream or distally in theleft common carotid artery. The coarctation constrictor is expanded toaugment cerebral blood flow to the left subclavian artery, the rightbrachiocephalic artery, and the right CCA. It will be understood thatcoarctation in the aorta increases the pressure gradient from the rightcerebral arteries and left vertebral artery to the left CCA, therebyenhancing flow reversal in the left CCA.

In another method, a coarctation constrictor is positioned in the aortaupstream or downstream of the left subclavian artery, and a secondconstrictor-occluder is positioned in the right common carotid artery orleft common carotid artery. Blood flow is reversed down the rightinternal carotid artery and into the right external carotid artery ordown the left internal carotid artery and into the left external carotidartery, when the constrictors are expanded. A filter may be located inthe external carotid artery to capture embolic debris. A thirdconstrictor may be located in the external carotid artery to enhance thepressure gradient between the internal carotid artery and externalcarotid artery to enhance flow reversal in the internal carotid artery.

After blood reversal is confirmed, procedures on either the vertebralartery, the internal carotid artery or branches thereof (e.g., MCA orACA), external carotid artery, or common carotid artery can be performedby advancing a therapeutic or diagnostic instrument through the lumenand port of the catheter distal to the occluder. An atherectomycatheter, for example, can be introduced to remove the atheroma in theright internal carotid artery without fear of distal embolization.

It will be understood that there are several advantages in using thedevices and methods disclosed herein for prevention of distalembolization during use of instrumentation in the carotid arteries. Forexample, the devices (1) abolish the need for suction distal to theconstricting/occluding member, thereby minimizing blood loss, (2)eliminate the need for systemic anticoagulation, pumping, and a secondarterial or venous stick, all of which are required where suction isemployed, (3) can be used to introduce a variety of diagnostic ortherapeutic instruments to the carotid arteries, (4) can be used in anyprocedures that require instrumentation within the carotid artery, (5)can be used for definitive treatment of acute or subacute ischemicstroke, (6) can be used in the angiogram or fluoroscopy suite availablein most hospitals, (7) usually require only one incision site for entry,and (8) can be used to perform an interventional procedure withoutdistal protection (e.g., a distal filter), and without crossing thelesion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts normal cerebral circulation in the Circle of Willis.

FIG. 2 depicts a reversed circulation in the Circle of Willis tocompensate for an occlusion in the left internal carotid artery.

FIG. 3 depicts a reversed circulation in the Circle of Willis tocompensate for an occlusion in the left vertebral artery.

FIG. 4A depicts a distal region of an embodiment of the medical devicehaving an occluding member for prevention of acute stroke during use ofinstrumentation in a carotid artery.

FIG. 4B depicts a distal region of another embodiment of the medicaldevice having a constricting member.

FIG. 5A depicts another embodiment of the device having a proximaloccluder and a distal constrictor.

FIG. 5B depicts another embodiment of the device having a proximalconstrictor and a distal constrictor.

FIG. 5C depicts another embodiment of the device having a proximalconstrictor and a distal occluder.

FIG. 5D depicts another embodiments of the device having a proximaloccluder and a distal occluder.

FIG. 6A depicts the device of FIG. 5C inserted in the rightbrachiocephalic artery through the descending aorta.

FIG. 6B depicts the expanded occluder in the brachiocephalic artery andexpanded constrictor in the descending aorta causing reversal of bloodflow from the internal carotid artery to the subclavian artery.

FIG. 6C depicts an angioplasty balloon catheter inserted through thedevice in FIG. 6B to treat an occluding lesion in the right internalcarotid artery.

FIG. 6D depicts a filter inserted through the catheter of FIG. 6C in theright subclavian artery to capture embolic debris.

FIG. 6E depicts a filter inserted in the right subclavian artery tocapture embolic debris generated by the angioplasty catheter of FIG. 6C.

FIG. 6F depicts the use of an occluder to establish carotid flowreversal, a second balloon to protect the vertebral artery againstembolization, and a constrictor to achieve aortic coarctation.

FIG. 6G depicts a constrictor placed in the aorta and an occlusioncatheter introduced through the right subclavian artery to treat anatheromatous lesion in the right internal carotid artery.

FIG. 6H depicts a filter mounted on the catheter of FIG. 6G to captureembolic debris in the right subclavian artery.

FIG. 7A depicts the device of FIG. 5B inserted in the rightbrachiocephalic artery.

FIG. 7B depicts the expanded constricting members in the rightbrachiocephalic artery and the aorta causing reversal of blood flow fromthe common carotid artery to the subclavian artery.

FIG. 7C depicts an atherectomy catheter inserted through the device inFIG. 7B to treat an occluding lesion in the right common carotid artery.

FIG. 7D depicts a filter inserted through the catheter of FIG. 7C anddeployed in the right subclavian artery to capture embolic debris.

FIG. 7E depicts the method shown in FIG. 7C with a filter inserted inthe right subclavian artery in a retrograde direction.

FIG. 8 depicts an alternative embodiment of the device inserted in theright brachiocephalic artery and the right subclavian artery to furtherincrease the pressure gradient between the right common carotid arteryand the right subclavian artery.

FIG. 8A depicts the method shown in FIG. 8 with a filter inserted in theright subclavian artery in a retrograde direction.

FIG. 9 depicts the constricting members of the device of FIG. 5Bconstricting the descending aorta and the inlets of the left commoncarotid artery and the left subclavian artery.

FIG. 9A depicts the method shown in FIG. 9 with a filter inserted in theleft subclavian artery in a retrograde direction.

FIG. 10 depicts an aortic constriction catheter capable of causing flowreversal down the left CCA.

FIG. 10A depicts a filter inserted through the catheter of FIG. 10 anddeployed in the left subclavian artery to capture embolic debris.

FIG. 11 depicts treatment of a left internal carotid lesion using aorticcoarctation and an occlusion catheter capable of bridging between theleft common carotid artery and the left subclavian artery.

FIG. 11A depicts treatment of a left internal carotid lesion usingaortic coarctation and an occlusion catheter capable of bridging betweenthe left CCA and the left subclavian artery downstream of the leftvertebral artery to prevent embolization into the left vertebral artery.

FIG. 11B depicts a filter mounted on the catheter of FIG. 11 andexpanded in the right subclavian artery upstream the takeoff of the leftvertebral artery to capture embolic debris.

FIG. 12A depicts the device of FIG. 5 inserted in the rightbrachiocephalic artery through the descending aorta to treat a lesion inthe right vertebral artery.

FIG. 12B depicts a filter inserted through the catheter of FIG. 12A inthe right subclavian artery to prevent distal embolization.

FIG. 12C depicts the device of FIG. 5 inserted in the right subclavianartery through the descending aorta to treat a lesion in the rightvertebral artery.

FIG. 12D depicts the method shown in FIG. 12C with a filter inserted inthe right subclavian artery in a retrograde direction to prevent distalembolization.

FIG. 12E depicts treatment of a lesion in the right vertebral arteryusing an occlusion catheter inserted through the left subclavian arteryand a constrictor catheter inserted in the descending aorta.

FIG. 12F depicts a filter mounted on an angioplasty catheter of FIG. 12Ein the right subclavian artery to prevent distal embolization.

FIG. 12G depicts treatment of a lesion in the right vertebral arteryusing an occlusion catheter inserted through the right subclavian arteryand a constrictor catheter inserted in the descending aorta.

FIG. 12H depicts a filter mounted on the catheter of FIG. 12G in theright subclavian artery to prevent distal embolization.

FIG. 13 depicts an aortic constriction catheter capable of causing flowreversal down the left vertebral artery.

FIG. 13A depicts a filter mounted on the angioplasty catheter of FIG. 13and expanded in the left subclavian artery to prevent distalembolization.

FIG. 14 depicts reversal of blood flow down the basilar artery using thedevice of FIG. 5C having the occlusion balloon positioned in the rightsubclavian artery, a coarctation balloon in the aorta, and a catheterhaving an occlusion balloon positioned in the left subclavian artery.

FIG. 14A depicts the method shown in FIG. 14 with filters expanded inthe right and left subclavian arteries to prevent distal embolization tothe arms.

FIG. 15A depicts reversal of blood flow from the right internal carotidartery into the right external carotid artery during angioplasty of aninternal carotid lesion.

FIG. 15B depicts reversal of blood flow from the right internal carotidartery into the right external carotid artery with filter protection inthe right ECA during stent treatment of an internal carotid lesion.

FIG. 16 depicts reversal of blood flow in the cerebral circulationduring treatment of a lesion in the right carotid siphon using thedevice of FIG. 5C.

FIG. 17 depicts incision sites on various peripheral arteries for theinsertion of the medical devices.

DETAILED DESCRIPTION

The cerebral circulation is regulated in such a way that a constanttotal cerebral blood flow (CBF) is generally maintained under varyingconditions. For example, a reduction in flow to one part of the brain,such as in stroke, may be compensated by an increase in flow to anotherpart, so that CBF to any one region of the brain remains unchanged. Moreimportantly, when one part of the brain becomes ischemic due to avascular occlusion, the brain compensates by increasing blood flow tothe ischemic area through its collateral circulation via the Circle ofWillis. FIG. 1 depicts a normal cerebral circulation and formation ofCircle of Willis. Aorta 100 gives rise to right brachiocephalic trunk82, left common carotid artery (CCA) 80, and left subclavian artery 84.The brachiocephalic artery further branches into right common carotidartery 85 and right subclavian artery 83. The left CCA gives rise toleft internal carotid artery (ICA) 90 which becomes left middle cerebralartery (MCA) 97 and left anterior cerebral artery (ACA) 99. Anteriorly,the Circle of Willis is formed by the internal carotid arteries, theanterior cerebral arteries, and anterior communicating artery 91 whichconnects the two ACAs. The right and left ICA also send right posteriorcommunicating artery 72 and left posterior communicating artery 95 toconnect respectively with right posterior cerebral artery (PCA) 74 andleft PCA 94. The two posterior communicating arteries and PCAs, and theorigin of the posterior cerebral from basilar artery 92 complete thecircle posteriorly. The left CCA also gives rise to external carotidartery (ECA) 78, which branches extensively to supply most of thestructures of the head except the brain and the contents of the orbit.The ECA also helps supply structures in the neck.

When occluding lesion 70 occurs acutely in left internal carotid artery90, as depicted in FIG. 2, blood flow in the right cerebral arteries,left external carotid artery 78, right vertebral artery 76, and leftvertebral artery 77 increases, resulting in a directional change of flowthrough the Circle of Willis to compensate for the sudden decrease ofblood flow in the left internal carotid artery. Specifically, blood flowreverses in right posterior communicating artery 72, right PCA 74, andleft posterior communicating artery 95. Anterior communicating artery 91opens, reversing flow in left ACA 99, and flow increases in the leftexternal carotid artery, reversing flow along left ophthalmic artery 75,all of which contribute to flow in left ICA 90 distal to the occludinglesion.

When occluding lesion 70 occurs acutely, for example, in left vertebralartery 88, as depicted in FIG. 3, blood flow in the left cerebralarteries, left external carotid artery 78, and right vertebral artery 76increases, resulting in a directional change of flow through the Circleof Willis down basilar artery 92 to compensate for the sudden decreaseof blood flow in the left vertebral artery. Specifically, blood flowreverses in right posterior communicating artery 72, right PCA 74, andleft posterior communicating artery 95. Although main collateral bloodflow to the left vertebral artery occurs through the right vertebralartery and the Circle of Willis, blood flow may also reverse incommunicating branch 130 of left vertebral artery 88 with the leftoccipital artery, left anterior cervical artery, and left thyrocervicalartery. The collateral blood flow through the posterior collateralcirculation becomes important when the right vertebral artery isatretic.

When an occlusion occurs in the basilar artery (not shown), blood flowin the right and left cerebral arteries, internal carotid arteries, andexternal carotid arteries increases, resulting in a directional changeof flow through the Circle of Willis down the basilar artery tocompensate for the sudden decrease of blood flow. Specifically, bloodflow reverses in right and left posterior communicating arteries, andright and left PCA's.

Balloon catheters for achieving flow reversal in carotid arteries weredescribed in Barbut, U.S. Pat. No. 6,146,370, incorporated herein byreference in its entirety. FIG. 4A depicts one embodiment of a devicefor preventing distal embolization during use of carotidinstrumentation. The device comprises catheter 1 and balloon occluder10. The catheter has lumen 5 communicating with a proximal end and port6 at a distal end. The lumen and port are adapted for introduction oftherapeutic or diagnostic instruments, e.g., an atherectomy catheter,angioplasty catheter, and stent, to a carotid artery. Balloon occluder10, communicating with inflation lumen 11, is mounted on the distal endof the catheter proximal to port 6. Pressure measuring device 15 isincluded distal to occluder 10 for monitoring blood pressure downstreamthe occluder. The pressure-measuring device can be a manometer or ablood flow channel that communicates with a pressure gauge at a proximalend of the device FIG. 4B depicts another embodiment of the devicehaving constricting member 20 mounted on a distal region of the catheterproximal to port 6. Constricting member 20 communicates with inflationlumen 21. The constrictor has central opening 22 that allows passage ofblood. Pressure measuring device 15 is mounted distal to constrictor 20for monitoring blood pressure downstream the constrictor.

FIGS. 5A, 5B, 5C, and 5D depict alternative devices for use in theinventions described herein. Each catheter has first balloon 10 andsecond balloon 20. All combinations of constrictors and occluders arecontemplated. Thus, first balloon 10 may be an occluder, and secondballoon 20 may be a constrictor (FIG. 5A). Alternatively, first balloon10 may be a constrictor, and second balloon 20 may be a constrictor(FIG. 5B). Alternatively, first balloon 10 may be a constrictor, andsecond balloon 20 may be an occluder (FIG. 5C). Alternatively, firstballoon 10 may be an occluder, and second balloon 20 may be an occluder(FIG. 5D). Balloon constrictor 10 is disposed in a distal region offirst elongate tubular member 4, and constrictor 20 is disposed in adistal region of second elongate tubular member 2. Each of balloonconstrictor 10 and constrictor 20 communicates with a respectiveinflation lumen (not shown). Constrictor 10 and constrictor 20 havecentral openings 12 and 22, respectively, that allow passage of blood.Elongate tubular member 4 includes a lumen and port 23 adapted forinsertion of therapeutic instruments, e.g., an angioplasty catheter,atherectomy catheter, or stent deployment catheter, into a vessel.Elongate tubular member 4, in certain embodiments, is slidably insertedthrough elongate tubular member 2, and is moveable longitudinallyrelative to elongate member 2 and constrictor 10. Manometers 15 aremounted distal to constrictors 10 and 20 for measuring blood pressuredownstream the constrictors. Any of the manometers of any devicedescribed herein will be understood to include a tube communicating witha pressure gauge at the proximal end of the catheter.

In using the device of FIG. 5C to treat an occluding lesion in the rightinternal carotid artery, for example, a percutaneous incision is firstmade on a peripheral artery, such as the femoral artery. A guidewire isinserted through the incision into the right brachiocephalic artery inan antegrade direction. The distal end of the catheter is inserted overthe guidewire, so that occluder 10 is positioned in rightbrachiocephalic artery 82 and constrictor 20 is positioned in thedescending aorta as shown in FIG. 6A; where needed, a guiding cathetercan also be used. Elongate member 4 is slides through elongate member 2to position constrictor 20 in the descending aorta. The guidewire isthen removed from the catheter.

In FIG. 6B, occluder 10 is slowly expanded to constrict rightbrachiocephalic artery 82 causing progressive decline in rightbrachiocephalic and right CCA pressure. Constrictor 20 is then slowlyexpanded to constrict the aorta, thereby causing augmentation ofcollateral blood flow down right ICA 86 by increasing blood flow to theleft CCA and left subclavian artery via the circle of Willis.Alternatively, constrictor 20 is expanded prior to expanding occluder10. The pressure in right brachiocephalic artery 82 distal to occluder10 and the pressure in the descending aorta distal to constrictor 20 canbe measured by manometers 15. At a critically low pressure in thebrachiocephalic artery, blood flow in right ICA 86 and CCA 85 reversesdown toward the brachiocephalic artery and into right subclavian artery83. The reversal of blood flow down the CCA and up the subclavian arterycan be verified fluoroscopically with dye.

After blood reversal is established from the CCA to the subclavianartery, the devices and methods described above can be used in anycarotid procedures. For example, in FIG. 6C, interventional catheter 30carrying angioplasty balloon 31 is introduced through lumen 5 and port 6of the device. The angioplasty balloon is shown expanding overatheromatous lesion 70 in right ICA 86, thereby compressing the lesionand enlarging the lumenal diameter. Compression of the atheroma by theangioplasty balloon often generates embolic debris, including calcium,atheromatous plaque, and thrombi. With reversal of blood flow from theICA to the CCA and into the right subclavian artery, distal embolizationto the intracranial cerebral arteries is avoided, thereby minimizingrisk of ischemic stroke. Distal embolization of the branches of thesubclavian artery has far less devastating consequences than the ICA.Blood flow through the affected subclavian artery and its branches isreduced but not abolished due to collateral circulation. For example,collateral flow is established from right vertebral artery 203 intoright subclavian artery 83, and this flow reversal in the vertebralartery protects against infarction in the posterior circulation,including the brain stem. In the event that flow reversal does not occurin the vertebral artery upon brachiocephalic occlusion, second balloon204 (see FIG. 6F) is positioned within the takeoff to the vertebralartery to protect against infarction in the posterior circulation.Filter 50 may be inserted through lumen 5 and deployed in rightsubclavian artery 83 to capture embolic debris generated duringangioplasty as shown in FIG. 6D, thereby preventing embolization to theright arm. Alternatively, filter 50 may be inserted retrograde throughright subclavian artery 83, the right radial artery, or the rightbrachial artery, and deployed in right subclavian artery 83 to captureembolic debris as shown in FIG. 6E.

Alternatively, treatment of a right ICA lesion using angioplasty andflow reversal down the right ICA into the right subclavian artery can beachieved by using a catheter adapted for retrograde insertion into theright subclavian artery as shown in FIG. 6G. Aortic coarctation toaugment blood flow to the contralateral circulation is achieved byplacing the device of FIG. 4B in the descending aorta through a femoralartery. Occlusion member 10 is expanded in the right brachiocephalicartery to establish flow reversal from the right CCA to the rightsubclavian. Catheter 30, here an angioplasty catheter, is advancedthrough port 201 to access stenosis 70 in right ICA 86. Filter 50 may bealternatively mounted on the catheter of FIG. 6G and expanded to captureembolic debris as shown in FIG. 6H, thereby preventing emboli fromtraveling downstream to occlude the arteries of the right arm.

In using the device of FIG. 5B to treat an occluding lesion in the rightcommon carotid artery, for example, the distal end of the device isfirst inserted into right brachiocephalic artery 82 as shown in FIG. 7A.Constricting member 20 is positioned in the descending aorta by slidingelongate member 4 through elongate member 2. Constricting member 10 isthen expanded to constrict the lumen of the brachiocephalic artery,causing reversal of blood flow from right CCA 85 toward brachiocephalicartery 82 and into right subclavian artery 83 as shown in FIG. 7B.Constrictor 20 is also expanded to increase blood flow to left CCA 80and left subclavian artery 84, thereby causing augmentation ofcollateral circulation down right common carotid artery 85.Alternatively, constrictor 20 is expanded in the aorta prior toexpanding constrictor 10 in the right brachiocephalic artery. Afterreversal of blood flow is verified angiographically, a therapeuticinstrument, such as an atherectomy catheter as depicted in FIG. 7C, isinserted through lumen 5 and port 6 to treat the occluding lesion.Embolic debris generated during the procedure is diverted from CCA 85toward subclavian artery 83, thereby preventing distal cerebralembolization and ischemic stroke.

In FIG. 7D, expandable filter 50 may be inserted through lumen 5 of thecatheter of FIG. 7C and deployed in right subclavian artery 83 toprevent embolic debris generated during the angioplasty procedure fromtraveling downstream to occlude the arteries of the right arm.Alternatively, filter 50 may be inserted in right subclavian artery 83in a retrograde direction from the radial artery, the brachial artery,or the right subclavian artery as shown in FIG. 7E.

The construction of atherectomy catheters is well known in the art andwill not be repeated in detail here. The reader is referred instead toFischell, U.S. Pat. No. 5,409,454; Fischell, U.S. Pat. No. 4,898,575;Rydell, U.S. Pat. No. 4,857,045; Yock, U.S. Pat. Nos. 4,794,931,5,000,185, and 5,313,949; Jang et al., U.S. Pat. No. 5,507,292; Farr,U.S. Pat. Nos. 4,950,277, 4,986,807, 5,019,088; Shiber, U.S. Pat. Nos.4,894,051, 4,957,482, 4,979,939, 5,007,896, 5,024,651, 5,135,531;Summers, U.S. Pat. No. 5,087,265; Plassche et al., U.S. Pat. No.5,318,576; Belknap, U.S. Pat. No. 5,366,464; Jang et al., U.S. Pat. No.5,402,790; Mazur et al., Catherization and Cardiovascular Diagnosis31:79-84 (1994); Fischell et al., U.S. Pat. Nos. 4,886,061, 5,100,425;and Barbut et al., U.S. Pat. No. 5,662,671, all of which areincorporated herein by reference in their entirety as if fully set forthherein. In other embodiments, catheter 35 may carry angioplasty balloon36 or a stent.

If flow reversal does not occur due to insufficient blood flow fromcontralateral circulation to the CCA, i.e., an insufficient pressuregradient between the CCA and the subclavian artery, a third constrictingmember 25 mounted distal to constrictor 10 can be used in certainembodiment to further increase the pressure gradient between the CCA andthe subclavian artery as shown in FIG. 8. In use, the distal end of thedevice is inserted into right brachiocephalic artery 82. The separationbetween occluder 10 and constrictor 25 is adjusted to ensure properplacement in the respective arteries. Preferably, occluder 10 is slowlyexpanded by injection through inflation lumen 11 to constrictbrachiocephalic artery 82, causing progressive decline of pressure inthe subclavian artery. Constrictor 20 in the aorta is then expandedslowly to increase blood flow to the left CCA and left subclavian arteryto augment collateral blood flow down right CCA 85. The pressure in thesubclavian artery distal to constrictor 10, the pressure in thesubclavian artery distal to constrictor 25, and the aortic pressuredistal to constrictor 20 can be measured by manometers 15. At acritically low pressure in the distal brachiocephalic artery, blood flowin CCA 85 reverses toward the brachiocephalic artery and into thesubclavian artery. The reversal of blood flow down the CCA and up thesubclavian artery can be verified fluoroscopically with dye. If flowreversal does not occur due to insufficient pressure gradient betweenthe CCA and the subclavian artery, constrictor 25 is gradually expandedto further reduce the pressure in the subclavian artery to create a morefavorable pressure gradient between the CCA and the subclavian artery toreverse blood flow into the subclavian artery. Filter 50 may be insertedretrograde in right subclavian artery 83 as shown in FIG. 8A to preventdistal embolization in the right arm.

In treating an occluding lesion in the left common carotid artery, thedistal end of the device of FIG. 5B is shown inserted in the inlets ofleft CCA 80 and left subclavian artery 84 as depicted in FIG. 9.Occluding member 10 is expanded to limit blood flow from the aorta intothe left CCA and the left subclavian artery. Constrictor 20 is alsoexpanded slowly to cause an increase in blood flow to the rightbrachiocephalic artery, right CCA, and right subclavian artery, therebyaugmenting collateral blood flow down left CCA 80 via the circle ofWillis. After blood flow reverses from left CCA 80 and into leftsubclavian artery 84, a therapeutic instrument, such as a stent isinserted through the lumen of elongate tubular member 4 and port 6. Thestent is shown deployed over the atheromatous lesion in left CCA 80,thereby compressing the lesion and enlarging the lumenal diameter. Withreversal of blood flow from the CCA to the subclavian artery, distalembolization of debris generated by compression of the atheromatouslesion to the intracranial cerebral arteries is avoided, therebyminimizing risk of ischemic stroke. In FIG. 9A, filter 50 may beinserted in left subclavian artery 84 in a retrograde direction toprevent embolization to the arteries of the left arm.

Flow reversal from left CCA 80 to left subclavian 84 can also beaccomplished by placing constricting member 10 of device FIG. 4B in theaorta between the brachiocephalic artery and the left CCA as shown inFIG. 10. After flow reversal is accomplished, angioplasty catheter 30 isdeployed through port 201 to access lesion 70. In FIG. 10A, filter 50may be inserted through port 201 and expanded to capture embolic debristraveling to left subclavian artery 84.

FIG. 11 depicts an alternative embodiment wherein first and secondoccluding members 10 are expanded to occlude each of the left CCA andleft subclavian artery. This device is introduced, for example, throughthe left subclavian artery. Flow reversal from left CCA 80 to leftsubclavian artery 84 is established through tubular member 202 mountedat the distal end of catheter 1. Expansion of constrictor 20 placed inthe descending aorta increases blood flow to right brachiocephalicartery 82, right CCA 85, and right subclavian artery 83 and facilitatesflow reversal from left CCA 80 to left subclavian artery 84.Interventional catheter 30 is deployed through tubular member 202 intoleft CCA 80. In FIG. 11A, second occluding member 10 is located in theleft subclavian artery downstream of the left vertebral artery toprevent embolization into the left vertebral artery. Alternatively,optional filter 50, mounted on catheter 30 or catheter 1, is positionedand expanded in left subclavian artery 84 upstream the takeoff of leftvertebral artery 88 as shown in FIG. 11B to prevent embolic debris fromtraveling distally into the left vertebral artery and the leftsubclavian artery.

Flow reversal from the right vertebral artery having an occluding lesiondown the ipsilateral subclavian artery can also be achieved by placing aconstrictor in the ipsilateral brachiocephalic artery and a constrictorin the descending aorta as shown in FIG. 12A. The distal end of thedevice of FIG. 5B is inserted and advanced into right brachiocephalicartery 82 upstream the takeoff of right common carotid artery 85.Constricting member 10 is slowly expanded, causing a reduction in theblood pressure (to approximately 20 mmHg) downstream the constrictor. Asa result, a favorable pressure gradient is created between the rightvertebral artery distal to the occluding lesion (typically havingpressure of approximately 40 mmHg) and the subclavian artery, causingreversal of blood flow from the vertebral artery into the subclavianartery. Reversal of blood flow from right common carotid artery 85 intothe subclavian artery also occurs due to the pressure differentialbetween the CCA and the subclavian artery. Expansion of constrictor 20in descending aorta 100 further increases the pressure gradient betweenthe right vertebral artery distal to the occluding lesion and the rightsubclavian artery by increasing collateral blood flow to the occludedright vertebral artery 87 through increasing blood flow to leftvertebral artery 88 and the left CCA via circle of Willis. Filter 50, asshown in FIG. 12B, may be inserted through the catheter and expanded inright subclavian artery 83 to prevent embolic debris from travelingdownstream to the right arm.

Alternatively, reversal of blood flow down an occluded right vertebralartery can be achieved by inserting the distal end of the device of FIG.5B in right subclavian artery upstream the takeoff of the rightvertebral artery as depicted in FIG. 12C. Constricting member 10 isslowly expanded to constrict subclavian artery 83, causing progressivedecline in the blood pressure of the subclavian artery downstream theconstrictor. The pressure in the subclavian artery distal to theconstrictor can be measured by manometer 15. Constrictor 20 is expandedin descending aorta 100 to augment blood flow to left CCA 80 and leftsubclavian artery 88 and down right vertebral artery 87 via thecollateral circulation. The reversal of blood flow down the vertebralartery into the subclavian artery can be verified fluoroscopically withdye. After blood reversal is established, therapeutic devices, such asan atherectomy, angioplasty, and/or stenting catheter, can then beinserted through the lumen of the constricting device, or through anyother suitable percutaneous entry point, and advanced to treat theoccluding lesion. With reversal of blood flow down the vertebral arteryinto the subclavian artery, distal embolization to the intracranialarteries is avoided, thereby minimizing risk of stroke. Distalembolization of the branches of the subclavian artery that supply theextremity has far less devastating consequences than the arterialbranches which supply the brain stem. In FIG. 12D, optional filter 50may be inserted in right subclavian artery 83 in a retrograde directionto capture embolic debris.

Reversal of blood flow down an occluded right vertebral artery can alsobe achieved by inserting the occlusion catheter of FIG. 4A in rightsubclavian artery upstream the takeoff of the right vertebral arterythrough the left subclavian artery as shown in FIG. 12E. Angioplastycatheter 35 can be inserted through the lumen of catheter 11 or throughthe right subclavian artery as shown. Angioplasty catheter 35 may alsoinclude filter 50 as shown in FIG. 12F which is deployed in rightsubclavian artery 83 to capture embolic debris. After completion of theangioplasty procedure, filter 50 is collapsed and removed with thecaptured emboli, thereby preventing distal embolization to the rightarm.

In FIG. 12G, an embodiment having distal constrictor/occluder 10 andproximal constrictor/occluder 25 suitable for insertion in thesubclavian artery is inserted in right subclavian artery 83 to furtherreduce pressure in the subclavian artery downstream the takeoff of rightvertebral artery 87. Constricting/occluding member 10 is inserted andadvanced in the subclavian artery downstream to the takeoff of right CCA85 and constricting member 25 is advanced in the subclavian arterydownstream to the takeoff of right vertebral artery 87.Constricting/occluding member 10 is first expanded to constrict/occludethe subclavian artery. Constrictor 20 of the device of FIG. 4B isinserted in the descending aorta and expanded to increase blood flow tothe left CCA and left subclavian artery, thereby causing augmentation ofcollateral blood flow down right vertebral artery 87. If flow reversaldoes not occur due to insufficient blood flow from the right vertebralartery, i.e., insufficient pressure gradient between the right vertebralartery and the subclavian artery, constricting/occluding member 25 isexpanded to further reduce the pressure in the subclavian artery tocreate an even more favorable pressure gradient to reverse blood flowinto the subclavian artery from the vertebral artery. Catheter 1 mayalso include filter 50 as shown in FIG. 12H to capture embolic debris inright subclavian artery 83.

Reversal of blood flow down an occluded left vertebral artery 88 canalso be accomplished by placing constrictor 20 in the aortic trunkbetween the takeoff of the right brachiocephalic artery and the left CCAas shown in FIG. 13. Collateral blood flow down left vertebral artery 88is augmented by increased blood flow from the right brachiocephalicartery, right CCA, and right vertebral artery. After reversal of bloodflow is established, angioplasty catheter 35 is inserted into leftvertebral artery 88 through the left subclavian artery as shown to treatthe occluding lesion. In this manner, embolic debris generated duringthe procedure is forced down the vertebral artery and into the leftsubclavian artery, thereby avoiding distal embolization to the posteriorcerebral circulation. Alternatively, filter 50 may be mounted oncatheter 35 as shown in FIG. 13A to capture embolic debris and preventemboli from traveling distally into the left arm.

In treating an occluding lesion in the basilar artery, reversal of bloodflow from the basilar artery into the vertebral artery can also beaccomplished by inserting a first constricting member in a vertebralartery and a second constricting member in the contralateral subclavianartery upstream the takeoff of the contralateral vertebral artery.Alternatively, first and second constricting members are placed in theright and left subclavian arteries upstream the takeoff of therespective vertebral arteries. For example, in FIG. 14, constrictingmember 10 of a device as in FIG. 5B is inserted in an antegradedirection into right subclavian artery 83 upstream the takeoff of rightvertebral artery 87 through an incision on a peripheral artery, e.g.,the femoral artery. Constricting member 20 is positioned in thedescending aorta. Constricting member 25, mounted on catheter 49, isinserted in a retrograde direction into the left subclavian arteryupstream the takeoff of left vertebral artery 88. Constricting members10 and 25 are then expanded to constrict or occlude the subclavianarteries, causing a pressure drop in the vertebrobasilar junction.Constricting member 20 is slowly expanded to constrict the aorta toaugment collateral circulation down the basilar artery by increasingblood flow to the right and left carotid arteries. After flow reversalis established, introduction of therapeutic device(s) into the basilarartery can be achieved through the lumen of either catheter. Embolicdebris generated during the procedure(s) is diverted from the basilarartery into the vertebral arteries and into the subclavian arteries,thereby preventing devastating consequences of brainstem embolization.In FIG. 14A, first filter 50 may be inserted through lumen 5 of thecatheter to deploy in right subclavian artery 83, and second filter 50may be mounted on catheter 49 to expand in left subclavian artery 84 toprevent distal embolization to the right and left arms.

An alternative method using the flow reversal concept in treating anoccluding lesion in the right internal carotid artery is shown in FIG.15A. The components of the device for use in the CCA and ECA aredescribed in Barbut, U.S. Pat. No. 6,146,370, incorporated herein byreference in its entirety. The device includes first constricting member20, second constricting or occluding member 10, and optionally thirdconstricting member 60. Constricting member 60, when present, isinserted into right external carotid artery 79. Constricting oroccluding member 10 is positioned in right common carotid artery 85, andconstricting member 20 is positioned in the descending aorta.Preferably, constricting member 10 is first expanded to constrict thelumen of the right common carotid artery, causing progressive decline inthe right ECA pressure. Constricting member 60, when present, isexpanded to further reduce the right ECA pressure to create a favorablepressure gradient between the right ICA and the right ECA to reverseblood flow into the right ECA. Constrictor 20 may also be expanded toincrease blood flow to left CCA 80 and left subclavian artery 84,thereby augmenting collateral circulation down right internal carotidartery 86. Alternatively, constrictor 20 is expanded in the aorta priorto expanding constrictor 10 in the right common carotid artery. Afterreversal of blood flow is verified angiographically, a therapeuticinstrument, such as an atherectomy catheter, is inserted through lumen 5to treat the occluding lesion. Embolic debris generated during theprocedure is diverted from the right ICA 86 toward right ECA 79, therebypreventing distal cerebral embolization and ischemic stroke. This sametechnique can be used to reverse blood flow in the left ICA to the leftECA by locating occluding balloon 10 in the left CCA, constrictor 20 inthe descending aorta, and optional constrictor 60 in the left ECA.

Alternatively, to treat an occluding lesion in the right internalcarotid artery using the flow reversal from the ICA to the ECA, thedevice of FIG. 5C is inserted through the right subclavian artery asshown in FIG. 15B. Constricting member 60, when present, is positionedin right external carotid artery 79, and constricting member 10 ispositioned in right common carotid artery 85. Filter 50 may be insertedthrough lumen 5 and deployed downstream of constricting member 60. Acatheter carrying constricting member 20 is inserted in the descendingaorta. Preferably, constricting member 10 is first expanded to constrictthe lumen of the right common carotid artery, causing progressivedecline in the right ECA pressure. Constricting member 60, when present,is expanded to further reduce the right ECA pressure to create afavorable pressure gradient between the right ICA and the right ECA toreverse blood flow into the right ECA. Constrictor 20 is also expandedto increase blood flow to left CCA 80 and left subclavian artery 84,thereby augmenting collateral circulation down right internal carotidartery 86. Alternatively, constrictor 20 is expanded in the aorta priorto expanding constrictor 10 in the right common carotid artery. Afterreversal of blood flow is verified angiographically, a therapeuticinstrument, such as stent deployment catheter as shown, may be insertedthrough lumen 5 to treat the occluding lesion. Embolic debris generatedduring the procedure is diverted from the right ICA 86 toward right ECA79 and captured by filter 50, thereby preventing distal cerebralembolization and ischemic stroke.

In treating a lesion in right carotid siphon, for example, the distaldevice of FIG. 5 is first inserted in the right brachiocephalic arteryas shown in FIG. 16. Constrictor 10 is slowly expanded in the rightbrachiocephalic artery causing progressive decline in the rightbrachiocephalic and right CCA pressure. Constrictor 20 is then slowlyexpanded to constrict the descending aorta, thereby causing augmentationof collateral blood flow down the carotid siphon and right ICA 86 viathe circle of Willis by increasing blood flow to the left CCA and leftsubclavian artery. Alternatively, constrictor 20 is expanded prior toexpanding constrictor 10. After blood reversal is established,interventional catheter 35 can be inserted through the device, port 23,up the right CCA, and the right ICA (not shown) to treat the lesion inthe carotid siphon. Alternatively, interventional catheter 35 can beinserted through port 22, up the left CCA, left ICA, left carotidsiphon, and anterior communicating artery 91 of the circle of Willis toreach the right carotid siphon as shown. This alternative method may bedesirable because it avoids crossing the lesion in the right carotidsiphon, and because direct access to certain cerebral lesions, such asaterio-venous malformation, cerebral aneurysm, or highly stenoticatheroma, usually results in devastating complications, e.g., vascularrupture and/or hemorrhage.

FIG. 17 depicts different sites of entry for the devices disclosedherein. An incision can be made on any peripheral artery, such as rightfemoral artery 132, left femoral artery 120, right brachial artery 112,left brachial artery 110, right axillary artery 126, left axillaryartery 125, right subclavian artery 142, or left subclavian artery 140.

The length of catheter will generally be between 10 and 200 centimeters,preferably approximately between 30 and 150 centimeters. The innerdiameter of the catheter lumen will generally be between 0.2 and 0.8centimeters, preferably approximately between 0.3 and 0.5 centimeters.The diameter of the expanded occluder will generally be between 0.3 and2 centimeters, preferably approximately 0.5 and 1.0 centimeters. Thediameter of the expanded aortic constrictor will generally be between0.5 and 3.5 centimeters, preferably approximately 1.5 and 2.5centimeters. The foregoing ranges are set forth solely for the purposeof illustrating typical device dimensions. The actual dimensions of adevice constructed according to the principles of the present inventionmay obviously vary outside of the listed ranges without departing fromthose basic principles.

Although the foregoing invention has, for the purposes of clarity andunderstanding, been described in some detail by way of illustration andexample, it will be obvious that certain changes and modifications maybe practiced which will still fall within the scope of the appendedclaims. For example, the devices, features, and methods shown in anydescribed embodiment can be used in any other described embodiment. Itwill also be understood that occlusion-constrictor 10 may be used incombination with filter 50 with or without constrictor 20 in the aortafor each embodiment. Moreover, occlusion-constrictor 10 may be used incombination with constrictor 20 in the aorta with or without filter 50for each embodiment.

What is claimed is:
 1. A method for reversing blood flow in a cerebralartery, comprising the steps of: locating a first constricting member inthe right brachiocephalic artery upstream of the right common carotidartery; locating a second constricting member in the aorta downstream ofthe left common carotid artery; expanding the first constricting memberto at least partially obstruct the right brachiocephalic artery; andexpanding the second constricting member to at least partially obstructthe aorta, wherein flow in the right common carotid artery is reversedto pass into the subclavian artery.
 2. The method of claim 1, whereinblood flow is reversed in the right internal carotid artery.
 3. Themethod of claim 1, further comprising the steps of advancing aninterventional catheter into a right cerebral artery and performing aprocedure on a lesion in the right cerebral artery.
 4. The method ofclaim 3, wherein the right cerebral artery is selected from the groupconsisting of the right common carotid artery, right internal carotidartery, right external carotid artery, right vertebral artery, carotidsiphon, MCA, and ACA.
 5. The method of claim 3, wherein theinterventional catheter is an angioplasty catheter.
 6. The method ofclaim 3, wherein the interventional catheter is an atherectomy catheter.7. The method of claim 3, wherein the interventional catheter is a stentdelivery catheter.
 8. The method of claim 1, further comprising the stepof deploying a filter in the right subclavian artery to capture embolicdebris.